Historically, cleaners used to clean air conditioning coils, electronic air filters and other types of metal filters have been sold in fairly concentrated liquid form, typically in 1 gallon, 5 gallon and 55 gallon containers. The servicemen would mix the product with water (typically 2 or 3 parts water to one part cleaner) in a 1, 2, or 3 gallon pump sprayer, then spray the diluted product onto the surface that needed to be cleaned.
Typically, three types of cleaners are used-acid coil cleaners, non-acid coil cleaners and evaporator coil cleaners. Acid coil cleaners include hydrofluoric acid as the active ingredient and are used on condenser coils located outdoors. Non-acid coil cleaners include either sodium hydroxide, potassium hydroxide or a combination of the two as the active ingredient and can be used on both condenser and evaporator coils. Evaporator coil cleaners are typically high alkaline cleaners formulated with various surfactants. They are used primarily on evaporator coils located indoors but can be used on condenser coils outdoors as well.
Several problems exist with the current liquid cleaners such as storage space and transportation requirements, spilling or leakage, and dilution errors.
The current demand for higher efficiency systems has caused air conditioning (A/C) units to become larger, thereby occupying significantly more space in the wholesaler's or the serviceman's warehouse. Liquid coil cleaners also occupy significant warehouse space. Liquid coil cleaners are purchased in case quantities (4 gallons per case) that take up a little more than one cubic foot per case and cases are bought in pallet quantities taking up 48 cubic feet of space or approximately a 3 ft×4 ft area. Liquid coil cleaners also take up significant storage space in a serviceman's truck, since about 8 gallons of cleaner or 2 cubic feet of truck space is required for one day of service calls.
It is not uncommon for a serviceman to accidentally puncture the liquid coil cleaner container in the truck and have highly corrosive liquids spill and damage the truck and tools. Wholesalers have similar problems with containers forming leaks when bottles are knocked off shelves or fork-lift trucks puncture cases of the liquid cleaner. Such spilled liquid cleaners can corrode floors, shelves and other merchandise.
Servicemen can also err in diluting concentrated cleaners. Without some type of additional measuring device it can be very difficult to accurately blend 2 or 3 parts water to one part cleaner and mix it in a pump-up sprayer. Servicemen habitually generate “diluted” cleaners that are either too dilute or too concentrated.
Furthermore, liquid cleaners, typically contain 70 to 80 wt. % water, which adds additional freight cost due to added weight and additional charges for transporting hazardous liquid formulations.
Prior attempts have been made by others to address some of these problems. A powdered cleaner, EV COIL MAX® is available from Highside Chemicals, Inc., Gulfport, Miss., USA. This product is reported to contain sodium metasilicate pentahydrate (a hazardous respirable dust with a 2 mg/m3 recommended ceiling) and sodium lauryl sarcosine. While this product is prepackaged for 1 gallon dilution, the instructions suggest further dilution to up to 3 gallons. Hence, the mixing problem still exists. A second powdered cleaner, HL COIL BRITE™ is also available from Highside Chemicals, Inc., Gulfport, Miss., USA. This product is an acid based coil cleaner containing ammonium bifluoride (ABF; ammonium hydrogendifluoride) a hazardous respirable dust that can cause fluorosis, hypocalcemia and hypomagnesia. Another product, Instant Powder Kegs™, is available from Controlled Release Technologies, Inc., Clearwater, Fla., USA. This product contains sodium silicate and is combined with sodium hydroxide, a corrosive alkaline product.